(1) Field of the Invention
The present invention relates to a valve apparatus for use in a proportional control mechanism extensively used in air-conditioning and other systems for controlling cold or hot water. More particularly, the invention relates to a valve apparatus suited primarily to a proportional electric two-way valve, which prevents vibrations of a valve closing member, suppresses turbulence occurring when controlling water, and prevents noise and vibrational and other abnormal sounds occurring with turbulent flows, thereby controlling water very quietly.
(2) Description of the Prior Art
With the spread of various types of air-conditioning system and the remarkable improvement in their performance achieved in recent years, there has been a strong demand for a function to control room temperatures automatically and reliably.
Generally, opening and closing of a valve apparatus have been used as means for stopping and allowing water flows through piping in a cold/hot water supply mechanism for room temperature control.
Most of the ordinary air-conditioning systems employ a valve mechanism which is electrically controlled to stop and allow water flows through the piping. When the valve closing member of the valve mechanism is closed, water flows are stopped suddenly thereby entailing what is known as water hammering to increase the water pressure suddenly. As a result, the water flows become turbulent in the valve bore and valve chamber of the valve mechanism, and the turbulent flows produce abnormal sounds such as frictional noise, impact noise and vibrational noise which propagate as resonances from the valve into the room.
Quiet environment is required for rooms whose temperature is controlled by the proportional control system, such as hospital wards, laboratories and hotels at nighttime. It has been an important subject matter imposed on the industry to provide a drastic solution to the problem of such abnormal sounds however slight they may be.